CONFIG_WALNUT is not available for thedefaultarchitecture x86.
Result is shown for architecture ppc

Walnut

modulename: walnut.ko

configname: CONFIG_WALNUT

Machine Type
└─>Walnut
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
This option enables support for the IBM PPC405GP evaluation board.

source code: